Which term describes the process by which a receptor becomes less responsive after repeated stimulation?

Which term describes the process by which a receptor becomes less responsive after repeated stimulation?

• A. Desensitization
• B. Sensitization
• C. Tolerance
• D. Activation

Answer: (A)

Desensitization explains why a receptor becomes less responsive after repeated stimulation. When a receptor is repeatedly activated by an agonist, the signaling pathway can adapt: the receptor may get phosphorylated, which uncouples it from its G protein, and receptors can be internalized, reducing their presence on the cell surface. These changes blunt the downstream signal, so the same amount of ligand elicits a smaller response over time. This is distinct from sensitization (increased responsiveness) and activation (the act of triggering signaling), and while tolerance describes reduced effect to a drug in a broader sense, desensitization specifically refers to the receptor’s waning responsiveness after repeated stimulation. Tachyphylaxis is a rapid form of desensitization, if that rapid timescale is involved.

Desensitization explains why a receptor becomes less responsive after repeated stimulation. When a receptor is repeatedly activated by an agonist, the signaling pathway can adapt: the receptor may get phosphorylated, which uncouples it from its G protein, and receptors can be internalized, reducing their presence on the cell surface. These changes blunt the downstream signal, so the same amount of ligand elicits a smaller response over time. This is distinct from sensitization (increased responsiveness) and activation (the act of triggering signaling), and while tolerance describes reduced effect to a drug in a broader sense, desensitization specifically refers to the receptor’s waning responsiveness after repeated stimulation. Tachyphylaxis is a rapid form of desensitization, if that rapid timescale is involved.